Stock Photo - 21 November 2022, Saxony-Anhalt, Thale: Two professional fishermen sail across the Rappbode Dam in a boat. They set their nets every few days to fish the dwarf whitefish out of the lake. The small fish was introduced in the 1960s, as potential food for the large predatory fish. The reproductive power of the dwarf whitefish was underestimated at the time. It is estimated that dwarf whitefish now make up about 95 percent of the biological fish mass in the reservoir. In the long run, this could become a threat to water quality. Therefore, about 3 tons of the vendace are fished out of the lake every year. The fishermen are on the lake for several months for this purpose. Photo: Matthias Bein/dpa. - Thale/Saxony-Anhalt/Germany